1. Field of the Invention:
The present invention relates to a method of automatically judging a film frame position.
2. Description of the Prior Art:
In a typical conventional method of judging a film frame position, a plurality of photosensors are disposed in a direction orthogonal to the longitudinal direction of a film, and the degree of density at each of the measuring points on the film is represented by each of the light/dark binary signals in accordance with the quantity of light passing through the film and received by each of the photosensors. Then, the OR (logical sum) of the binary signals is obtained, and when an OR changing width which is obtained when the film is conveyed in its longitudinal direction takes a value in the vicinity of a predetermined value (e.g., 36 mm), a frame position is declared.
However, such a judging method requires the detection of edges at both ends of a frame in the longitudinal direction of the film and it is not therefore possible by this method to detect a frame position when one of the frame edges is insufficiently clear.
On the other hand, if the light-receiving area of each of the photosensors is reduced for the purpose of increasing the resolving power, then it becomes impossible for a frame edge to be regarded as a straight line, and in such a case, the above-described method may lead to a misjudgement of the type wherein, for example, a portion of the film outside an actual edge is judged to be a frame edge. For this reason, it is not possible to increase the degree of accuracy in judgement of a frame position simply by improving the resolving power of each of the photosensors.